Separating walls in adjoining Class 1 buildings

We need to talk about separating walls and what the building certifier means when they refer to separating walls. Separating walls are essential to protect against noise and fire, but choosing the right installation or modifying an older system, can seem quite a daunting task. Here is The Oil Stone’s quick discussion.

Before we start, I want to make it very clear that a Separating Wall means a wall that is common to adjoining Class 1 buildings. They are not used in any other class of building other than Class 1, so you will only find the term Separating Wall in the Building Code of Australia Volume 2. This is the red one for Class 1 and 10 buildings.

The first thing to know about separating walls is that they start at the ground and finish at the underside of the non-combustible roof covering. Separating walls cannot start at the floor if the floor is above ground level, nor can they finish at a ceiling. They must extend to the underside of the non-combustible roof. We’ve provided a more in depth explanation of the difference between Class 1 and Class 2 dwellings here.

For Class 1a dwelling units, the installation of separating walls used to be very simple. Often a masonry wall, or a framed wall with some fire rated sheeting, was enough to achieve the required fire and noise rating. This simplicity has been changing and doesn’t look to stop any time soon. These days, the walls must achieve a fire rating, sound rating, impact rating, and in some cases, they have to be discontinuous construction.

These changes mean that the wall systems used in the past now need all sorts of additions and modifications to comply with the current standards. While this seems a big task, you might be surprised at the new systems becoming available that not only achieve the requirements, but also speed up construction, saving time and money.

There are also options out there that use the performance provisions of the BCA to allow the sound requirements to be reached with the ceiling instead of the wall above the ceiling.

The Oil Stone is not about promoting any particular product, so we would like to invite all the suppliers and readers out there to provide their own input.

Suppliers, tell us about your Separating Wall systems. Do they tick all the boxes? And what are the advantages?

And readers, we would love to hear your feedback also. What separating wall systems are you using, and are you happy with the result?

Related posts:

I am a Director of Development Certification Pty Ltd and have been a Building Surveyor since 1989. I have a bachelor degree in building surveying and I am a qualified carpenter. I have been in the construction industry since 1981. I have a real passion for the building certification profession as I believe building certifiers are the general practitioners of the construction industry. Our role is not only to know building law and apply it, our role includes assisting in the development of the knowledge of all in the industry by sharing our knowledge and experience.